314 research outputs found
Multiple scattering effects on heavy meson production in p+A collisions at backward rapidity
We study the incoherent multiple scattering effects on heavy meson production
in the backward rapidity region of p+A collisions within the generalized
high-twist factorization formalism. We calculate explicitly the double
scattering contributions to the heavy meson differential cross sections by
taking into account both initial-state and final-state interactions, and find
that these corrections are positive. We further evaluate the nuclear
modification factor for muons that come form the semi-leptonic decays of heavy
flavor mesons. Phenomenological applications in d+Au collisions at a
center-of-mass energy GeV at RHIC and in p+Pb collisions at
TeV at the LHC are presented. We find that incoherent multiple
scattering can describe rather well the observed nuclear enhancement in the
intermediate region for such reactions.Comment: 10 pages, 6 figures, published version in PL
Fractal Metamaterial Absorber with Three-Order Oblique Cross Dipole Slot Structure and its Application for In-band RCS Reduction of Array Antennas
To miniaturize the perfect metamaterial absorber, a fractal three-order oblique cross dipole slot structure is proposed and investigated in this paper. The fractal perfect metamaterial absorber (FPMA) consists of two metallic layers separated by a lossy dielectric substrate. The top layer etched a three-order oblique fractal-shaped cross dipole slot set in a square patch and the bottom one is a solid metal. The parametric study is performed for providing practical design guidelines. A prototype with a thickness of 0.0106λ (λ is the wavelength at 3.18 GHz) of the FPMA was designed, fabricated, measured, and is loaded on a 1×10 guidewave slot array antennas to reduce the in-band radar cross section (RCS) based on their surface current distribution. Experiments are carried out to verify the simulation results, and the experimental results show that the absorption at normal incidence is above 90% from 3.17 to 3.22GHz, the size for the absorber is 0.1λ×0.1λ, the three-order FPMA is miniaturized 60% compared with the zero-order ones, and the array antennas significantly obtain the RCS reduction without the radiation deterioration
Flavor dependence of jet quenching in heavy-ion collisions
We investigate the flavor dependence of jet quenching, by performing a
systematic analysis of medium modifications on the inclusive jet, +jet,
and -jet in Pb+Pb collisions at the LHC. Our results from MadGraph+PYTHIA
and LBT exhibit excellent agreement with experimental measurements of the
inclusive jet, +jet and -jet simultaneously both in p+p and Pb+Pb
collisions. We then utilize a Bayesian data-driven method to extract
systematically the flavor-dependent jet energy loss distributions from
experimental data, where the gluon, light quark and -quark initiated energy
loss distributions are well constrained. It is shown that the quark-initiated
jet energy loss distribution shows weaker centrality and dependence than
the gluon-initiated one. We demonstrate the impacts of the slope of initial
spectra,color-charge as well as parton mass dependent jet energy attenuation on
the -jet suppression observed in heavy-ion collisions.Comment: 9 pages, 7 figure
The origin of summer monsoon rainfall at New Delhi by deuterium excess
International audienceThe deuterium excess in summer monsoon precipitation, determined from isotopic measurements(?18O and Keywords: deuterium excess, relative humidity, origin of precipitatio
eHIJING: an Event Generator for Jet Tomography in Electron-Ion Collisions
We develop the first event generator, the
electron-Heavy-Ion-Jet-Interaction-Generator (eHIJING), for the jet tomography
study of electron-ion collisions. In this generator, energetic jet partons
produced from the initial hard scattering undergo multiple collisions with the
nuclear remnants with a collision rate that is proportional to the
transverse-momentum-dependent (TMD) gluon densities in the nucleus.
Medium-modified QCD parton splittings within the higher-twist and generalized
higher-twist framework are utilized to simulate parton showering in the nuclear
medium that takes into account the non-Abelian Landau-Pomeranchuck-Midgal
interference in gluon radiation induced by multiple scatterings. The TMD gluon
distribution inside the nucleus is given by a simple model inspired by the
physics of gluon saturation. Employing eHIJING, we revisit hadron production in
semi-inclusive deep inelastic scattering (SIDIS) as measured by EMC, HERMES as
well as recent CLAS experiments. eHIJING with both the higher-twist and
generalized higher-twist framework gives reasonably good descriptions of these
experimental data. Predictions for experiments at the future electron-ion
colliders are also provided. It is demonstrated that future measurements of the
transverse momentum broadening of single hadron spectra can be used to map out
the two dimensional kinematic () dependence the jet transport
parameter in cold nuclear matter.Comment: 27 pages, 27 figure
Unraveling Gluon Jet Quenching through Production in Heavy-Ion Collisions
Jet quenching has long been regarded as one of the key signatures for the
formation of quark-gluon plasma in heavy-ion collisions. Despite significant
efforts, the separate identification of quark and gluon jet quenching has
remained as a challenge. Here we show that in high transverse momentum
() region provides a uniquely sensitive probe of in-medium gluon
energy loss since its production at high is particularly dominated
by gluon fragmentation. Such gluon-dominance is first demonstrated for the
baseline of proton-proton collisions within the framework of leading power
NRQCD factorization formalism. We then use the linear Boltzmann transport model
combined with hydrodynamics for the simulation of jet-medium interaction in
nucleus-nucleus collisions. The satisfactory description of experimental data
on both nuclear modification factor and elliptic flow
reveals, for the first time, that the gluon jet quenching is the driving force
for high suppression. This novel finding is further
confirmed by the data-driven Bayesian analyses of relevant experimental
measurements, from which we also obtain the first quantitative extraction of
the gluon energy loss distribution in the quark-gluon plasma.Comment: 7 pages, 5 figures, version published in Science Bulleti
A High‐resolution Atmospheric Dust Record for 1810–2004 A.D. Derived from an Ice Core in Eastern Tien Shan, Central Asia
Centennial‐scale, high‐resolution records of atmospheric dust conditions are rare in the arid and semiarid regions of central Asia, limiting our understanding of the regional climate and environmental changes and their potential driving forces. In this paper, we present an annually resolved atmospheric dust record covering the period of 1810–2004 A.D., reconstructed from an ice core retrieved at 4512 m above sea level from the Miaoergou Glacier in the eastern Tien Shan. The time series of dust flux for the past 195 years shows three periods of relatively low values (i.e., 1810–1829 A.D., 1863–1940 A.D., and 1979–2004 A.D.) and two periods of relatively high values (i.e., 1830–1862 A.D. and 1941–1978 A.D.). Spatial correlation analysis suggests possible regional factors controlling the dust flux, including antecedent summer precipitation, spring soil moisture, and near‐surface wind speed. In addition, the Miaoergou dust flux is closely associated with the winter index of the North Atlantic Oscillation (NAO) over the past two centuries, with high (low) dust periods coinciding with the negative (positive) phases of the NAO. The persistent relationship suggests that the NAO may have been a key driver on dust flux change over the arid regions between the Tien Shan and Kunlun Mountains
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